The National Weather Service in Sullivan has expanded a flash flood watch to include all of southern Wisconsin, including the Milwaukee metro area.

"Widespread showers and thunderstorms will develop by late evening, moving through southern Wisconsin through early Saturday morning," according to a statement from the weather service. "One to two inches of rainfall are likely, with locally higher amounts possible."

The flash flood watch is in effect from 7 p.m. Friday through Saturday afternoon.

"We’re going to probably have two rounds," of rain, said Marcia Cronce, a weather service meteorologist in Sullivan. "We’re going to have an evening round and then we’ll get into the more persistent round that is going to be after midnight tonight.

"The rainfall rates are going to be very efficient, very high," she added. "What that means is when it rains, it’s going to actually pour."

That's not normal for early October in southern Wisconsin.

"This is not typical," Cronce said. "We have an exceptionally high amount of moisture in the atmosphere in our area for this time of year. It’s just the way the upper air pattern is right now."

The concern is that "we’re going to just get rain for a long period of time at the same location," Cronce said. Pinpointing exactly where the heaviest rain will fall remains a question.

"Somewhere in our vicinity," Cronce said. "That’s why we have the (flash flood) watch in effect."

One area of concern, according to the weather service, is "...Madison and southwest of there toward Darlington, where recent heavy rainfall has caused river and lake flooding problems."

Areas shaded in dark green are under a flash flood watch through Saturday afternoon, Oct. 6, 2018. The lighter green areas show areas where flood advisories are already in place.(Photo11: National Weather Service - Millwaukee/Sullivan office)